Polymeric derivatives of bicycloheptene as stabilizers for polymer compositions



United States Patent POLYMERIC DERIVATIVES OF BHCYCLOHEPTENE AS STABHLIZERS FOR POLYMER CUMPQSITIONS John R. Caldwell and John W. Tamloiyn, Kingsport,

Tenn, assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Apr. 27, 1960, Ser. No. 24,886

Ill Claims. (Cl. 106-180) This invention relates to plastic compositions composed of vinyl resins or of cellulose esters which are stabilized against degradation during exposure to heat. More particularly this invention concerns the use of polymeric esters of bicyclo (2.2.1)-5heptene-2,3-dicarboxylic acid with certain glycols.

Plastic materials such as the vinyl polymers and cellulose esters are subject to various types of thermal degradations caused by traces of mineral acids, present either as initial impurities or generated in the plastic during exposure to heat. In the cellulose esters, this degradation takes the form of molecular-weight breakdown with consequent loss of strength and toughness. In the polyvinyl plastics such as polyvinyl chloride, degradation takes the form of discoloration.

In the past various types of acid absorbers have been used to produce stabilization of these plastics against the damaging effects of heat. For instance, alkaline inorganic pigments like magnesium carbonate or organic acid absorbers such as the epoxy compounds have been widely used for this purpose. The organic absorbers have been considered more efiective than the inorganic absorbers. However, for general use, particularly for films and fibers, a stabilizer which has less tendency to escape from the plastic by evaporation or leaching is desirable for maximum permanence of stabilizing action. We have found that certain polymeric derivatives containing the bicycloheptene structure satisfy this need. These derivatives are low-molecular-Weight polyesters made condensing bicyclo- (2.2.l)-5-heptene-2,3- dicarboxylic acid with certain glycols.

One object of this invention is to provide a plastic material from cellulose esters or polyvinyl materials stabilized against degradation from exposure to heat. An-

180 C. for two hours in a nitrogen atmosphere. The temperature is then raised to 220 C. and held for three hours. The product is a viscous syrup having a molecular weight of 600400 that was soluble in the common solvents such as acetone, alcohol, and methylene chloride.

Butenediol-1,4, propylene glycol or butylene glycol may be used in place of ethylene glycol.

The low-molecular-weight polyesters used in the process I of the invention may be prepared by using a ratio of 2-5 molecular proportions of bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid, or suitable derivative, with 3-6 molecular proportions of the glycol. The acid may be used in the form of its anhydride or lower alkyl ester. When the polymer is made with butenediol, it is preferred to use a lower alkyl ester of the acid, and an ester interchange catalyst such as titanium butoxide, litharge, or calcium oxide. e

The reaction is preferably carried out in two stages. In the first stage the reactants are heated at l40-l80 C. for 2-4 hours and in the second stage at ZOO-220 C. for 2-4 hours.

The, polyesters have a molecular weight in the range of 500-1800.

The following examples. are intended to illustrate ourinvention but are not intended to limit it in any way:

EXAMPLE 1 Polyvinyl chloride (Geon 101) was roll-compounded with 30% by weight of dioctyl phthalate and sheeted off the roll in the form of slabs mils thick. Similar compoundings were prepared containing, in addition, 4% by weight of the short-chain length polyester made from bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid and ethylene glycol or 4% by weight of the short-chain length Table I C Stabilize olor of sample after heating 30 min. 60 min. min. 1 min.

None Light brown Brown Dark b Bieycloheptena polyester with ethylene glycol Light orange Orange Rednu ffi h r l ied. Bicycloheptene polyester with butenediol do Light orange Reddish orange-.. Reddish brown.

other object of this invention is to provide a process for EXAMPLE 2 stabilizing cellulose esters and polyvinyl chloride plastic compositions against deterioration at elevated temperatures. An additional object is to provide a material which may be used for stabilizing organic plastic materials against heat degradation. A further object is to provide a low-molecular-weight polyester from bicyclo-(2.2.1)-5- heptene-2,3-dicarboxylic acid.

To prepare the polymeric composition which we have found extremely suitable for stabilizing plastic materials against heat, three molecular proportions of bicyclo- (2.2.l)-5-heptene-2,3-dicarboxylic anhydride and four molecular proportions of ethylene glycol are heated at Cellulose acetate butyrate (13% acetyl, 38% butyryl) was roll-compounded with 12% by weight of dibutyl sebacate and sheeted off the roll in the form of slabs 75 mils thick. Similar compoundings were prepared con stantial improvement in the resistance of cellulose acetate butyrate plastic to discoloration by heat.

Samples of these same compositions were heated for plastic. In these tests the polyester made from the saturated glycol appeared somewhat better than that from the unsaturated glycol.

Table [1 Color of sample after heating Stabilizer min 105 min. 140 min. 170 min.

No Yellow Yellow-l \rown Brown. Bicyclolleptane polyester with ethylene glycol Light yello\\ Light yellow Light yellow. Bicycloheptene polyester with butenediol -do lo .Do.

half an hour at 250 C. and the degradation of the cellulose acetate butyrate determined by measurement of the inherent viscosity, {1;}, before and after heating. {1;} was Table IV defined as:

I Color of sample after heating Stabilizing plasticizor c 40 min. 70 min. 100 min.

where n, is the ratio of the viscosity of solution to that q k. of solvent and c 15 the concentration of the cellulose gf fl g ggg g5515.555; Omme Dakmd brown mac acetate butyrate in g. per 100 cc. solvent. The solvent y i gf y le egcoi h 's goyellown 823531.06 used was acetone, the temperature 25.0 C., and the i concentration of the cellulose ester 0.23 g. per 100 cc. acetone. {1 before heating had the value of 1.40. The breakdown results, recorded in Table III, show a worth while im rovement roduce b addition of the bio clo- P d y y EXAMPLE 4 heptene esters.

The same samples were also heated at 205 C. for one and two hours. The color developed after these heating periods was graded by comparison with a set of color standards. Color before heating was also determined and these color results included in Table III.

6 mils thick. Similar films were made from dopes to which had been added in one case 4 g. of diethylbicyclo- (-2.2.1)-5-heptene-2,3-dicarboxylate and in the other case Table III 4' g. of the ethylene glycol polyester of Example 1.

Samples of these films were suspended in a mechanical Color after 0 40 convection oven at 125 C. and observed every two hours Stabilizer 62 Original f gff for weight loss and development of color. The results, 250 0. color given in Table V, show that the monomeric stabilizer 1 1m 2 hr protects the resin well only until it is lost from the film by evaporation. Over 75% of this stabilizer escaped dur- None Q51 35 60 so ing six hours heating. The superiority of the polymeric g i e lpolyester with 0 0 stabilizer is clearly demonstrated for the longer heat treat- Bi .l i?..ZZ gggfgg 35 7 ments. Practically none of this stabilizer escaped during butenediol 0. s0 40 e0 65 six hours heating.

Table V STABILIZATION OF VYNS FILMS Wei htloss ercent) afte heatin at 125 Color after heating at 125 C. for- C. for

2 hr. 4 hr. 6 hr. 0 hr. 2 hr. 4 hr. 6 hr. 8 hr.

None 2. 90 3.06 3.11 None. Light yellow-brown. Yellow-brown Yellow -hrown Yellow-brown, Diethylbicyclo-(2.2.1)-5-11eptene-2, 13.2 15.4 16.7 ..d0 None L1ghtpurple...-- BroWmsh-purple. PlllpllSllbroWn.

3-d' bo' late. Bicybl l iepl ne polyester with 2.16 2.36 2.51 .do..- Very pale straw Very pale straw" Pale straw. Pale straw.

ethylene glycol.

EXAMPLE 3 EXAMPLE 5 Compoundings like those of Example 1 were prepared except that where the bicycloheptene polyesters were included 30% by weight of each, instead of 4% by weight, was used. They were thus employed as secondary, stabilizing plasticizers. Heat tests, similar to-those of Example l-gave the results shown in.Table IV. Here, again, the samples containing the bicycloheptene polyesters showed much better color stability than the unstabilized Secondary cellulose acetate (39% acetyl) was dissolved in acetone to make a dope containing 15% by weight of the cellulose ester. This was cast on a glass plate as a film 5 mils thick when dry. This film was heated in air on the glass plate at 250 C. for a half hour. The percentage loss of inherent viscosity, calculated as in Example 2, was determined and listed in Table VI. A similar film containing 4% by weight of the butenediol polyester of Example 1, was prepared and tested in the same way. The result was also recorded in Table V1 for comparison with the unstabilized film. Several other cellulose esters were similarly tested with and without the butenediol polyester stabilizer and the results included in Table VI. It may be seen that substantial stabilization was in all cases obtained. In the case of the triacetate and tributyrate esters a solvent consisting of 90 parts by volume of methylene chloride and parts by volume of methanol was used.

Cellulose esters which may be stabilized using our new polymeric stabilizer include all of the lower alkyl cellulose esters including secondary cellulose acetates, cellulose triacetates, secondary cellulose propionates, cellulose tripropionate, secondary cellulose butyrate, cellulose tributyrate, cellulose acetate propionates, cellulose acetate butyrate, and cellulose propionate butyrate. Other esters which may be used include cellulose valerates, caproates, pelargonates, caprates, etc. Esters of cellulose with carboxylic acids containing 2 to 10 carbon atoms are within the scope of our invention.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as described in the appended claims.

This application is a continuation-in-part of U.S. application Serial No. 638,441, filed February '6, 1957, now U.S. Patent No. 2,950,265.

We claim:

1. A plastic composition consisting essentially of a cellulose ester obtained by esterifying cellulose with a carboxylic acid having 2-10 carbon atoms and a stabilizing amount of a polyester having a molecular weight of 500-1800 made by condensing bicyclo-(2.2.1)-5-heptene- 2,3-dicarboxylic acid with a glycol selected from the class consisting of ethylene glycol, propylene glycol, butylene glycol, and butenediol-l,4.

2. A plastic composition consisting essentially of a cellulose ester obtained by esterifying cellulose with a carboxylic acid having 2-10 carbon atoms and a stabilizing amount of a polyester having a molecular weight of 500-1800 made by condensing bicyclo-(2.2.1)-5-heptene- 2,3-dicarboxylic acid with ethylene glycol.

3. A plastic composition consisting essentially of a cellulose ester obtained by esterifying cellulose with a carboxylic acid having 2-10 carbon atoms and a stabiliz- 6 ing amount of a polyester having a molecular weight of 500-1800 made by condensing bicyclo-(2.2.1)-5-heptene- 2,3-dicarboxylic acid with propylene glycol.

4. A plastic composition consisting essentially of a cellulose ester obtained by esterifying cellulose with a carboxylic acid having 2-10 carbon atoms and a stabilizing amount of a polyester having a molecular weight of 500-1800 made by condensing bicyclo-(2.2.1)-5-heptene- 2,3-dicarboxylic acid with butylene glycol.

5. A plastic composition consisting essentially of a cellulose ester obtained by esterifying cellulose with a carboxylic acid having 2-10 carbon atoms and a stabilizing amount of a polyester having a molecular weight of 500-1800 made by condensing bicyclo-(2.2.1)-5-heptene- 2,3-dicarboxylic acid with butenediol-1,4.

6. A plastic composition consisting essentially of cellulose acetate and a stabilizing amount of a polyester having a molecular weight of 500-1800 made by condensing bicyclo-(2.2.1)-5-heptene-2,S-dicarboxylic acid with a glycol selected from the class consisting of ethylene glycol, propylene glycol, butylene glycol, and butenediol- 1,4.

7. A plastic composition consisting essentially of cellulose butyrate and .a stabilizing amount of a polyester having a molecular weight of 500-1800 made by condensing bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid with a glycol selected from the class consisting of ethylene glycol, propylene glycol, butylene glycol, and butenediol- 1,4.

8. A plastic composition consisting essentially of cellulose acetate butyrate and a stabilizing amount of a polyester having a molecular weight of 500-1800 made by condensing bicyclo (2.2.1) 5 heptene-2,3-dicarboxylic acid with a glycol selected from the class consisting of ethylene glycol, propylene glycol, butylene glycol, and butenediol-l,4.

9. A plastic composition consisting essentially of cellulose acetate propionate and a stabilizing amount of a polyester having a molecular weight of 500-1800 made by condensing bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid with a glycol selected from the class consisting of ethylene glycol, propylene glycol, butylene glycol, and butenediol-l,4.

10. A plastic composition consisting essentially of cellulose propionate butyrate and a stabilizing amount of a polyester having a molecular weight of 5001800 made by condensing bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid with a. glycol selected from the class consisting of ethylene glycol, propylene glycol, butylene glycol, and butenediol-l,4.

11. A plastic composition consisting essentially of cellulose tributyrate and a stabilizing amount of a polyester having a molecular weight of 500-1800 made by condensing bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid with a glycol selected from the class consisting of ethylene glycol, propylene glycol, butylene glycol, and butenediol- 1,4.

References Cited in the file of this patent UNITED STATES PATENTS 2,576,268 Gershan et al. Nov. 27, 1951 2,697,045 Hetzel Dec. 14, 1954 2,742,371 Albus et al. Apr. 17, 1956 

1. A PLASTIC COMPOSITION CONSISTING ESSENTIALLY OF A CELLULOSE ESTER OBTAINED BY ESTERIFYING CELLULOSE WITH A CARBOXYLIC ACID HAVING 2-10 CARBON ATOMS AND A STABILIZING AMOUNT OF A POLYESTER HAVING A MOLECULAR WEIGHT OF 500-1800 MADE BY CONDENSING BICYCLO-(2,2.1)-5-HEPTENE2,3-DICARBOXYLIC ACID WITH A GLYCOL SELECTED FROM THE CLASS CONSISTING OF ETHYLENE GLYCOL, PROPYLENE GLYCOL, BUTYLENE GLYCOL, AND BUTENEDIOL-1,4. 